1. Field of the Invention
This invention relates in general to methods and apparatus for determining trimmed images of originals which are to be reproduced in the printing technology using optoelectrical original means.
2. Description of the Prior Art
In printing technology, there is a demand for most precise determination of the desired scale of reproduction for producing color separations by means of so-called scanners which produce color separations by means of photo-electrical optical scanning. For this purpose, enlargement devices are known and in the prior art, the enlargement or reduction is measured before actual scanning occurs and a color slide that is to be scanned is projected onto a projection table using the light source. At one side of the projection table there is provided a vertical support which carries the projection head which can be moved up and down with the motor. The desired scale can be set and read depending on the position of the projection head.
A vertical frame or beam member which carries the projection head can be moved up and down with a motor and the desired scale can be set and read depending on the position of the projection head.
It turns out in practice, however, that the operation of such devices is complicated and time consuming and the precision obtained depends a great deal on the skill of the particular operator.